The invention relates to the display of images.
High definition, multicolor display, low power consumption, lower voltage requirements and light weight have made liquid crystal displays (LCDs) a leading display device technology. LCDs have been used for several years as mobile information displays in, for example, personal digital assistants (PDAs), portable computers, mobile phones, and the like.
Recently, CMOS shift register circuits have been widely applied in Low Temperature Poly Silicon (LTPS) LCDs. However, at least eight masks are required to form the CMOS shift register circuit during fabrication, and thus, the costs are increased. For cost reduction, PMOS shift registers, which require fewer masks, are used frequently by LCD makers.
FIG. 1 shows a conventional signal driving circuit comprising PMOS shift registers. The PMOS shift registers shown, however, require four clock signals provided by an external application specific integrated circuit (ASIC) (not shown). Because of the increased clock signals, ASICs required the use of PMOS shift registers typically are more expensive.